Updated 11 August 2014

Treating sleep apnoea may lower blood pressure

People with sleep apnoea and hard-to-control high blood pressure may see their blood pressure drop if they treat the sleep disorder.

People with sleep apnoea and hard-to-control high blood pressure may see
their blood pressure drop if they treat the sleep disorder, Spanish researchers
report.

Continuous positive airway pressure (CPAP) is the standard treatment for
sleep apnoea, a condition characterised by disrupted breathing during sleep.
The sleep disorder has been linked to high blood pressure.

Patients in this study were taking three or more drugs to lower their blood
pressure, in addition to having sleep apnoea. Participants who used the CPAP
device for 12 weeks reduced their diastolic blood pressure (the bottom number
in a blood pressure reading) and improved their overall night-time blood
pressure, the researchers found.

"The prevalence of sleep apnoea in patients with resistant [high blood
pressure] is very high," said lead researcher Dr Miguel-Angel
Martinez-Garcia, from the Polytechnic University Hospital in Valencia.

Patients with resistant high blood pressure should undergo a sleep study to
rule out obstructive sleep apnoea, Martinez-Garcia said. "If the patient
has sleep apnoea, he should be treated with CPAP and undergo blood pressure
monitoring."

The report, published in the issue of the Journal of the American Medical
Association, was partly funded by Philips-Respironics, maker of the CPAP
system used in the study.

The CPAP system consists of a motor that pushes air through a tube connected
to a mask that fits over the patient's mouth and nose. The device keeps the
airway from closing, and thus allows continuous sleep.

Sleep apnoea is a common disorder. The pauses in breathing that patients
experience can last from a few seconds to minutes and they can occur 30 times
or more an hour.

As a result, sleep quality is poor, making sleep apnoea a leading cause of
excessive daytime sleepiness, according to the US National Heart, Lung, and
Blood Institute.

Overall effectiveness

Dr Gregg Fonarow, a spokesman for the American Heart Association and
professor of cardiology at the University of California, Los Angeles, agrees
that most patients with hard-to-control high blood pressure also suffer from
sleep apnoea.

"Close to three out of four patients with resistant [high blood
pressure] have been found to have obstructive sleep apnoea, and this sleep apnoea
may contribute to the difficulty to control the blood pressure in these
patients," he said.

Although this study showed a benefit from CPAP in controlling blood pressure,
questions remain about the treatment's overall effectiveness, Fonarow said.

"Whether these improvements in blood pressure can be sustained in the
long term and will translate to improved health outcomes will require
additional studies," he said.

Patients get used to it

According to the chief medical liaison for Philips Respironics, Dr Teofilo
Lee-Chiong, the CPAP device allows the patient to sleep, and thus lets the
blood pressure drop normally as it would at night.

"Patients have to get used to it, and most patients do," said
Lee-Chiong, who is also a professor of medicine at National Jewish Health at
the University of Colorado Denver.

The sound of the device is akin to a fan and can be lessened by placing the
device under the bed or using earplugs, he added.

The cost of CPAP machines vary but can range from a few hundred dollars to R
10 364.70, Lee-Chiong said. CPAP is covered by most insurance, including
Medicare, he noted.

For the study, Martinez-Garcia and colleagues randomly assigned 194 patients
with sleep apnoea and high blood pressure to CPAP or no CPAP. During the study
the patients continued to take their blood pressure medications.

Difference in systolic pressure

The researchers found that those receiving CPAP lowered their 24-hour
average blood pressure 3.1 mm Hg more than those not receiving CPAP.

In addition, those treated with CPAP had a 3.2 mm Hg greater reduction in
24-hour average diastolic blood pressure.

The difference in systolic pressure wasn't statistically significant between
the two treatment groups, the researchers noted.

Over the 12 weeks of the study, about 36% of those receiving CPAP had at
least a 10% drop in night-time blood pressure, compared with 22% of patients
not receiving CPAP, they added.

The systolic pressure, the top number, measures the pressure in the arteries
when the heart beats. The diastolic pressure, the bottom number, measures the
pressure in the arteries between beats.

Ask the Expert

Dr Alison Bentley is a general practitioner who has consulted in sleep medicine and sleep disorders, in both adults and children of all ages, for almost 30 years. She also researches and publishes on a number of sleep-related topics both in formal research journals and lay publications including as editor of Sleep Matters, an educational newsletter on sleep disorders for doctors.

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